Understanding Cookies and Sessions
Web Development Guidelines
06 Jul,2016
0
Cookies and Sessions are inextricably intertwined, and fundamental to creating rich, interactive internet applications.
What is a "Cookie"?
A cookie is a small piece of text stored on a user's computer by their browser. Common uses for cookies are authentication, storing of site preferences, shopping cart items, and server session identification.
Each time the users' web browser interacts with a web server it will pass the cookie information to the web server. Only the cookies stored by the browser that relate to the domain in the requested URL will be sent to the server. This means that cookies that relate to www.example.com will not be sent to www.exampledomain.com.
In essence, a cookie is a great way of linking one page to the next for a user's interaction with a web site or web application.
What is a "Session"?
A session can be defined as a server-side storage of information that is desired to persist throughout the user's interaction with the web site or web application.
Instead of storing large and constantly changing information via cookies in the user's browser, only a unique identifier is stored on the client side (called a "session id"). This session id is passed to the web server every time the browser makes an HTTP request (ie a page link or AJAX request). The web application pairs this session id with it's internal database and retrieves the stored variables for use by the requested page.